The present invention relates to a recording/reproducing optical disk, in which data recording/reproduction can be conducted by use of a sector disposed along a spiral track as a unit, and to an optical disk reproducing apparatus for data recording/reproducing on the optical disk.
Heretofore, rewritable optical disks available on the market have included optical disks having diameters of 120 mm and 90 mm and phase change disk of 120 mm in diameter (popular as PD).
These disks comprise guiding grooves for laser light illumination. Tracking is carried out by analyzing laser light based on the guiding grooves. The guiding grooves are formed as a continuous spiral which runs from the inner side of the disk to the outer side thereof. Heretofore, the guiding grooves each are referred to simply as xe2x80x9ca groovexe2x80x9d and a portion other than the grooves are referred to as xe2x80x9ca land.xe2x80x9d In a conventional optical disk, information has been recorded either in a groove or on a land.
Such information on an optical disk is read and written for example, in 512 bytes or 2048 bytes as a unit. This information unit is called xe2x80x9ca sector.xe2x80x9d In this sector, a sector address which indicates a location of the sector is assigned and formatting is conducted according a predetermined sector format in order to record information to a target address and to reproduce the information with high reliability. In the formatting, information on a sector is recorded by forming a recess/protrusion profile called xe2x80x9ca pitxe2x80x9d at a head of the sector. This portion in which the sector address information is recorded is called xe2x80x9ca header.xe2x80x9d In a conventional optical disk, as described above, since information has been recorded in either a groove or a land, the header must be either in a groove for groove recording, or on a land for land recording.
While a conventional optical disk has recorded information either in a groove or on a land as described above, the recording capacity of the disk can easily be increased if information is recorded on both the groove and the land.
However, a problem arises regarding formatting the sector address in a manner such that information can be recorded in both the land and the groove.
In a conventional optical disk provided with a spiral groove as described above, the groove and the land are formed parallel to each other, hereinafter referred to as a double spiral structure.
In a double spiral structure, since grooves and lands are formed in parallel to each other, travel from a groove to a land requires a track jump. Therefore, whenever recording/reproducing of information is switched from a groove to a land and vice versa, a track jump or a seek is necessary, thereby making continuous recording/reproducing of information difficult.
Additionally, the only way to manufacture a disk in the double spiral format, is to separately format a sector in a groove (hereinafter referred to as groove sector) and another sector on a land (hereinafter referred to as land sector). Thus, it becomes difficult to format a disk, for example by a zone CAV format, so that recording/producing of information can alternately be conducted on a land or in a groove adjacent to each other.
That is, in order for a land and a groove adjacent to each other, to have sector addresses numbered in a continuous manner, either the grooves or lands must be independently formatted, while being separately assigned with addresses in an intermittent manner. In this case, unless travel from a land to a groove or vice versa is smoothly performed, disk rotational delay time occurs, which causes a problem of interference with realization of continuous recording/reproducing of information.
In addition, its desirable to achieve as much distance between pits in a header as possible in order to perform a more stable reading of the header.
It is an object of the present invention to provide an optical disk information medium with higher reliability in reading a header and detecting a switch-over position between a land and a groove in a stabilized manner. Such an optical disk can be provided by disposing header areas on the optical disk in a zig-zag shifted manner using an optical disk fabricating apparatus for the same medium.
The present invention is directed to a data recording/reproducing optical disk comprising: a first recording section RF1, RF3, RF2, RF4, which is an area in the shape of a land formed on a spiral track, and in which data recording/reproducing is conducted; a second recording section RF5, RF7, RF6, RF8 adjacent to the first recording section, which is an area in the shape of a groove formed on the spiral track, and in which data recording/reproducing is conducted. Also provided is a first half header section HF1, HF3, in which first address information corresponding to the first recording section is recorded; and a second half header section HF2, HF4, in which second address information corresponding to the second recording section is recorded, and which is disposed in a zig-zag shifted manner in pair with the first half header section. The first half header section, e.g. HF1, and the second half header section, e.g. HF4, are located ahead of the first recording sections e.g. RF2. Additionally, both half header sections are located to assume a first positional relation relatively to the first recording section and when the first half header section, e.g. HF1, and the second half header section, e.g. HF2, are located ahead of the second recording section e.g. RF5, both half header sections are located to assume a second positional relation other than the first positional relation relative to the second recording section.
The present invention has a configuration in which the first half header section HF1, HF3 and the second half headers HF2, HF4 are disposed in a zig-zag shifted manner with a space therebetween as shown in FIG. 1A and therefore 1) reliability in reading is increased because a margin in distance between adjacent pits is provided, 2) a narrow beam exclusively used for a header is not necessary any longer and thus cutting can be possible by one beam with a high speed and 3) a switch-over position between a land and a groove can be detected with ease.
That is, according to a structure A as shown in FIG. 7, since there is no blank in a header section 103 lying between recording sections 101 and 105, a distance between pits is smaller and thereby creates the possibility of an error reading the error in data.
On the other hand, according to a structure C of the present invention, since a blank is provided, a sufficient margin is available in distance between pits, hereby reliability in address reading can be improved.
For this reason, since a cutting process also has a sufficient margin in distance between pits according to an embodiment of the present invention, one beam can commonly be used for cutting of recording and address sections and both cuttings are thereby conducted in one operation. Therefore, there is no requirement for having a beam uses exclusively for cutting a header, as is in the case of the structure A. Thus, a speedy cutting process can be realized.
In an optical disk having such a double spiral structure as used in the present invention, there is a necessity for detection of switch-over in tracking polarity between land and groove areas. A positional relation of the headers located in the zig-zag shifted manner, that is, wobbling of each header, can be used for detection of switch-over timing. That is, a photodetector cell, which analyzes a reflecting light from a disk, outputs a first signal A corresponding to the outer side of a recording track and a second signal B corresponding to the inner side thereof, and in addition detects the difference between the signals as (Axe2x88x92B). The signal difference (Axe2x88x92B) assumes (Axe2x88x92B) greater than 0 for a header which wobbles to the outer side, that is a positive sign [+] and on the other hand the difference assumes (Axe2x88x92B) less than 0 for a header which wobbles to the inner side, that is a positive sign [xe2x88x92]. With detection of the signal change in a header, a polarity change in signal of [xe2x88x92] to [+] (FIG. 8A) can determine that the header comes ahead of a recording section of the land sector and the polarity change in signal of [+] to [xe2x88x92] (FIG. 8B) can tell that the header comes head of a recording section of the group sector.
In addition, another embodiment of the present invention is directed to a data recording/reproducing optical disk comprising: a plurality of land sectors RF1, RF2, RF3, RF4, HF1, HF3, wherein a predetermined number of land sectors are disposed on a spiral track on a disk along one track round and the land sector is an area in the shape of a land where data recording/reproducing is conducted and disposed on the spiral track. The land sector includes a first recording section RF1, RF2, RF3, RF4 and a first half header section HF1, HF3, which indicates address information of the first recording section, and which is located ahead of the first recording section. A plurality of groove sectors RF5, RF6, RF7, RF8, HF2, HF4 is included, wherein a predetermined number of groove sectors are disposed on a spiral track on the disk along one track round. The predetermined number of groove sectors are disposed in parallel to the predetermined number of land sectors in an alternate manner. The plurality of groove sectors and the plurality of land sectors are disposed on tracks alternately continuously in a radial direction, one round of land sectors and one round of groove sectors being directly adjacent to each other. Additionally, a groove sector is an area in the shape of a groove where data recording/reproducing is conducted and disposed on the spiral track. The groove sector includes: a second recording section RF5, RF6, RF7, RF8 and a second half header section HF2, HF4, which has address information of the second recording section, and which is disposed ahead of the second recording section in a zig-zag shifted manner in pair with the first header section.
It is understood that in the present embodiment, the optical disk has a feature wherein a land area and a groove area are alternately disposed on the disk in a radial direction and thus a continuous recording area is provided. This feature is included in addition to the plurality of headers having a configuration in a zig-zag shifted manner.
In such a structure, improvement on reading reliability, speedy cutting with one kind of beam and easy detection of switch-over positions between land and groove sectors can be realized.
In yet another embodiment, the present invention is directed to a data recording/reproducing optical disk recording/reproducing apparatus using a data recording/reproducing optical disk comprising: a first recording section RF1, RF3, RF2, RF4, which is an area in the shape of a land formed on a spiral track, and in which data recording/reproducing is conducted. A second recording section RF5, RF7, RF6, RF8 adjacent to the first recording section is also provided, which is an area in the shape of a groove formed on a spiral track, and in which data recording/reproducing is conducted. A first half header section HF1, HF3, in which first address information corresponding to the first recording section is recorded; and a second half header section HF2, HF4, in which second address information corresponding to the second recording section is recorded, and which is disposed in a zig-zag shifted manner in pair with the first half header section, are included. The first half header section, e.g. HF1 and the second half header section e.g. HF4, are located ahead of the first recording sections e.g. RF2. Both half header sections are located to assume a first positional relation relative to the first recording section, and when the first half header section, e.g. HF1, and the second half header section, e.g. HF2, are located ahead of the second recording section e.g. RF5, both half header sections are located to assume a second positional relation other than the first positional relation relative to the second recording section. The apparatus comprises: light illuminating means for illuminating the first half header sections, the second half header section, the first recording section and the second recording second section with a light beam. Next, the apparatus includes control means for controlling an illuminating position of the light beam based on a change in characteristics of reflecting light of the light beam from the illuminating means in order to direct the light beam to a predetermined position on the optical disk. Finally included, are and data recording/reproducing means for detecting a switch-over position between the first recording section and the second recording section based on a reflecting light reflected from the first half header section and the second half header section produced by illumination of the light beam from the illuminating means and executing data recording/reproducing on the optical disk based on the detection of the switch-over position.
The present invention, as described above, is to provide with a data recording/reproducing optical disk recording/reproducing apparatus which executes read/write of data on the data recording/reproducing disk, and which has headers disposed in a zig-zag shifted manner. Thus, a switch-over position between a land section and a groove section can be reliably detected by detecting the wobble of each of the headers.
Furthermore, in a final embodiment of the present invention a data recording/reproducing optical disk recording/reproducing apparatus is provided, wherein a light beam is intentionally shifted toward the inner side of the optical disk by a predetermined deviation from the center of a track.
With use of the apparatus, a light beam spot can be traced in a condition that the light beam spot is maintained in the same track and not only when switch-over of tracking polarity is not conducted but even when switch-over of tracking polarity is not successfully conducted, normal tracking control can be assured without any radical deviation therefrom.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinbefore.